1,720,970 research outputs found
Study of the CdTe detector applied in digital oral radiology
Get PDFOrientadores: Deborah Queiroz de Freitas França, Francisco Haiter NetoTese (doutorado) - Universidade Estadual de Campinas, Faculdade de Odontologia de PiracicabaResumo: O presente estudo foi desenvolvido com objetivo de avaliar a qualidade da imagem, acurácia de diagnóstico e a dose de radiação obtidas com o receptor CdTe e compará-lo com os receptores CCD e CMOS. Um phantom de polímero sintético com formato de cabeça preenchido com água (Phantom 1) foi usado para aquisição de cinco imagens para avaliação objetiva. Cinco phantoms de crânio humano macerado com revestimento de polímero (Phantom 2) foram usados para obtenção das telerradiografias em norma lateral (TNL) para análise do diagnóstico e avaliação subjetiva da qualidade. Cinco tríades de dosímetros posicionados no phantom 2 foram expostos dez vezes seguidas, simulando aquisição de TNL, para dosimetria. Esses procedimentos foram realizados em aparelhos com cada tipo de receptor, com os padrões energéticos indicados para um adulto de porte médio. Para avaliação objetiva, cinco áreas da imagem foram selecionadas e foi mensurada a quantidade de ruído. Para o diagnóstico, três examinadores realizaram a análise de McNamara e uma classificação dentoesquelética e sete examinadores avaliaram subjetivamente as imagens. Os dados paramétricos obtidos nas diferentes análises foram comparados pela Análise de Variância one way, com Teste Tukey post hoc. Para a classificação dentoesquelética foi obtido índice Kappa. Houve diferença significante entre as imagens dos três receptores (p0,05) entre os receptores e foi observada concordância perfeita (Kappa = 1,0) entre a classificação dentoesquelética obtida nas imagens dos três receptores. A dose utilizada para o receptor CMOS foi superior à usada para o receptor CCD (p0.05) was observed between the detectors for the cephalometric analysis, and perfect agreement (Kappa = 1.0) was observed for the orthopedic-dental classification. The dose used for the CMOS detector was higher than that used for the CCD (p<0.001) and for the CdTe (p<0.001), but no difference was observed between the last two (p=0.452). Although the images obtained by the different receptors have no difference in the diagnostic task evaluated, the images obtained with the CdTe receptor were superior in the overall quality of the image. Therefore, considering the set of characteristics studied, it is recommended to use the CdTe receptor in clinical practiceDoutoradoRadiologia OdontologicaDoutora em Radiologia OdontológicaCAPE
Influence of metal artefact reduction tool in quality of CBCT images
No full textOrientador: Deborah Queiroz de Freitas FrançaDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Odontologia de PiracicabaResumo: Materiais de alta densidade física e alto número atômico quando presentes no objeto escaneado podem resultar em artefato nas imagens tomográficas. O artefato compromete a qualidade da imagem tomográfica, podendo inviabilizar o uso dessa modalidade de diagnóstico. Com este trabalho, teve-se dois objetivos: avaliar a ação da ferramenta de redução de artefato metálico (RAM) nas imagens tomográficas de phantoms com diferentes materiais utilizados na Odontologia (amálgama de prata, guta-percha e liga metálica) e avaliar a influência de diferentes tamanhos de campo de visão (field of view - FOV) e de voxel sobre a ação da ferramenta. Foram confeccionados três phantoms de resina acrílica com amostras dos materiais estudados em seu interior. Os phantoms foram escaneados no tomógrafo do aparelho Picasso Trio® (Vathec, Hwaseong, Coréia do Sul) com diferentes FOVs (120x85 mm, 80x80 mm, 80x50 mm e 50x50 mm) e voxels (0,3 mm e 0,2 mm). Todos os escaneamentos foram realizados duas vezes com cada parâmetro, uma sem ativação e uma com ativação da ferramenta de RAM. As imagens foram avaliadas no programa OnDemand3D (CyberMed, Seul, Coréia do Sul). Foram obtidos valores de média e desvio-padrão do histograma das áreas ao redor das amostras e das áreas-controle e foi calculada a relação contraste-ruído (RCR). Os dados foram submetidos à análise. Observou-se influência positiva da ferramenta nos valores do desvio-padrão das áreas ao redor das amostras dos materiais amálgama de prata e liga metálica. Não houve influência da utilização da ferramenta sobre os valores das médias e valores de RCR. Na presença da ferramenta de RAM, o FOV e o voxel não influenciaram os valores de desvio-padrão das áreas ao redor das amostras. Foi possível concluir que a ferramenta mostrou-se eficaz na redução do artefato gerado pelo amálgama de prata e pela liga metálica; e a ação da ferramenta não é influenciada por diferentes FOVs e voxels, de forma que esses parâmetros podem ser selecionados de acordo com o objetivo do exame, sem haver alterações quando a ferramenta é utilizadaAbstract: High density and high atomic number materials are scanned results in artefact in tomographic image. The artefact compromises the quality of tomographic image, which may make the image useless for the diagnosis. The aim of this study were: to assess the action of metal artefact reduction (MAR) algorithm on tomographic images of phantoms with different materials used in Dentistry (dental amalgam, gutta-percha and dental alloy); to assess the influence of different sizes of field of view (FOV) and voxel on the action of the MAR algorithm. Three phantoms were made of acrylic resin with the dentals materials in their interior. The phantoms were scanned on Picasso Trio® machine (Vathec, Hwaseong, South Korea) with different FOVs (120x85 mm, 80x80 mm, 80x50 mm and 50x50 mm) and voxels (0.3 mm and 0.2 mm). All scans were performed twice with each parameter, without and with activation of the MAR algorithm. The images were evaluated on the OnDemand3D software (CyberMed, Seoul, South Korea). The mean and variation (standard deviation - SD) of greyscale values of the histogram of the areas around samples and control areas were obtained. The contrast-to-noise ratio (CNR) was calculated. Data were statistically analyze. There was positive influence of the algorithm on the SD of the areas around the samples of dental amalgam and dental alloy. There was no influence of the algorithm on the mean of greyscale values and CNR. The FOV and voxel did not influence the SD of the areas around the samples when the MAR algorithm was active. In conclusion, the MAR algorithm showed positive effect in reducing the artefact caused by dental amalgam and dental alloy; its action was not influenced by different FOVs and voxels, so those parameters can be selected according to the examination purpose, as there are no changes in the algorithm useMestradoRadiologia OdontologicaMestra em Radiologia Odontológic
REGRESSÃO DE LESÃO PERIAPICAL EXTENSA DECORRENTE DE NECROSE PULPAR MEDIANTE TRATAMENTO ENDODÔNTICO – RELATO DE CASO
Get PDFEste trabalho foi desenvolvido com o objetivo de descrever o relato de caso de lesão periapical extensa, demonstrando que a completa remoção do fator causal por meio de tratamento endodôntico pode ser suficiente para obter êxito, tornando desnecessário a intervenção cirúrgica. O relato apresenta o caso de uma paciente, gênero feminino, 58 anos que apresentou alteração endodôntica originada de uma desordem inflamatória dos tecidos periapicais de origem endodôntica nos dentes 31 e 41. Clinicamente a lesão aparentou estar associada a lesão cariosa e/ou lesão recidivante. O tratamento foi fundamentado na eliminação do agente agressor mediante ao tratamento endodôntico mecânico e químico como primeira alternativa a fim de evitar a necessidade da intervenção cirúrgica proservando os tecidos Peri adjacentes ao dente
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
- …
